PERT model and formula
This formula has me to calculate each task to get a completion time frame from project completion to how long each task will take to complete. The PERT model can be in minutes, hours, days, months, and years. The formula is:
Expected Value = (Optimistic + (4 x Most Likely) + Pessimistic) / 6
EV = (10 + (4 x 15) + 20) / 6
EV = (10 + (60) +20) / 6
EV = (70 + 20) / 6
EV = (90) / 6
EV = 15 days is the time it should take me to finish the project.
The PERT model also has a confidence factor formula that will allow you to get a range of how confident you are to completing a task.
Standard Deviation = (Pessimistic – Optimistic) / 6
SD = (20 – 10) / 6
SD = (10) / 6
SD = 1.66 is my standard deviation
To calculate the range of the confidence factor, 87.5 is always plugged in to calculations.
Confidence Factor = 87.5 + (2 x SD)
Confidence Factor = 87.5 – (2 x SD)
CF = 87.5 + (2 x 1.66)
CF = 87.5 + (3.32)
CF = 90.82
CF = 87.5 – (2 x 1.66)
CF = 87.5 – (3.32)
CF = 84.18
My Confidence Factor range to completing this project in 15 days is 90.82 to 84.18 percent.
Now I need to calculate all my task completion and their confidence range.
PERT Project Schedule |
These tasks are measured in Hours.
Task |
Expected Value |
Standard Deviation |
Confidence Range |
Interviewing |
15hrs |
1.66hrs |
90.82% – 84.18% |
Scripting |
12hrs |
2hrs |
91.5% – 83.5% |
Filming |
48hrs |
4hrs |
95.5% – 79.5% |
Editing |
24.33hrs |
1.66hrs |
90.82% – 84.18% |